Commitments, Contingencies and Guarantees - Lending Commitments (Detail) - USD ($) $ in Millions |
Dec. 31, 2020 |
Dec. 31, 2019 |
|---|---|---|
| Commitments and Contingencies Disclosure [Abstract] | ||
| Held for investment | $ 162,513 | $ 150,100 |
| Held for sale | 6,594 | 8,091 |
| At fair value | 2,468 | 1,899 |
| Total | $ 171,575 | $ 160,090 |